Hello EZ, welcome to the forums and indeed so sorry as to what is happening with your son.
I can't diagnose him as I'm not doctor, however, can I make a suggestion as he's been unconscious and seeing a neurologist is that it maybe epilepsy which unfortunately I sustained from a head injury and developed this injury.
It does leave me with the same systems not knowing what day it is or even year until I can gather my senses and realise.
There are various degrees if somebody does have epilepsy.
Has it left your son feeling very tired?